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authorDavid Howells <dhowells@redhat.com>2006-10-05 09:55:46 -0400
committerDavid Howells <dhowells@warthog.cambridge.redhat.com>2006-10-05 10:10:12 -0400
commit7d12e780e003f93433d49ce78cfedf4b4c52adc5 (patch)
tree6748550400445c11a306b132009f3001e3525df8 /drivers/pcmcia/yenta_socket.c
parentda482792a6d1a3fbaaa25fae867b343fb4db3246 (diff)
IRQ: Maintain regs pointer globally rather than passing to IRQ handlers
Maintain a per-CPU global "struct pt_regs *" variable which can be used instead of passing regs around manually through all ~1800 interrupt handlers in the Linux kernel. The regs pointer is used in few places, but it potentially costs both stack space and code to pass it around. On the FRV arch, removing the regs parameter from all the genirq function results in a 20% speed up of the IRQ exit path (ie: from leaving timer_interrupt() to leaving do_IRQ()). Where appropriate, an arch may override the generic storage facility and do something different with the variable. On FRV, for instance, the address is maintained in GR28 at all times inside the kernel as part of general exception handling. Having looked over the code, it appears that the parameter may be handed down through up to twenty or so layers of functions. Consider a USB character device attached to a USB hub, attached to a USB controller that posts its interrupts through a cascaded auxiliary interrupt controller. A character device driver may want to pass regs to the sysrq handler through the input layer which adds another few layers of parameter passing. I've build this code with allyesconfig for x86_64 and i386. I've runtested the main part of the code on FRV and i386, though I can't test most of the drivers. I've also done partial conversion for powerpc and MIPS - these at least compile with minimal configurations. This will affect all archs. Mostly the changes should be relatively easy. Take do_IRQ(), store the regs pointer at the beginning, saving the old one: struct pt_regs *old_regs = set_irq_regs(regs); And put the old one back at the end: set_irq_regs(old_regs); Don't pass regs through to generic_handle_irq() or __do_IRQ(). In timer_interrupt(), this sort of change will be necessary: - update_process_times(user_mode(regs)); - profile_tick(CPU_PROFILING, regs); + update_process_times(user_mode(get_irq_regs())); + profile_tick(CPU_PROFILING); I'd like to move update_process_times()'s use of get_irq_regs() into itself, except that i386, alone of the archs, uses something other than user_mode(). Some notes on the interrupt handling in the drivers: (*) input_dev() is now gone entirely. The regs pointer is no longer stored in the input_dev struct. (*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking. It does something different depending on whether it's been supplied with a regs pointer or not. (*) Various IRQ handler function pointers have been moved to type irq_handler_t. Signed-Off-By: David Howells <dhowells@redhat.com> (cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)
Diffstat (limited to 'drivers/pcmcia/yenta_socket.c')
-rw-r--r--drivers/pcmcia/yenta_socket.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/drivers/pcmcia/yenta_socket.c b/drivers/pcmcia/yenta_socket.c
index 1344746381e8..26229d9da762 100644
--- a/drivers/pcmcia/yenta_socket.c
+++ b/drivers/pcmcia/yenta_socket.c
@@ -442,7 +442,7 @@ static int yenta_set_mem_map(struct pcmcia_socket *sock, struct pccard_mem_map *
442 442
443 443
444 444
445static irqreturn_t yenta_interrupt(int irq, void *dev_id, struct pt_regs *regs) 445static irqreturn_t yenta_interrupt(int irq, void *dev_id)
446{ 446{
447 unsigned int events; 447 unsigned int events;
448 struct yenta_socket *socket = (struct yenta_socket *) dev_id; 448 struct yenta_socket *socket = (struct yenta_socket *) dev_id;
@@ -478,7 +478,7 @@ static void yenta_interrupt_wrapper(unsigned long data)
478{ 478{
479 struct yenta_socket *socket = (struct yenta_socket *) data; 479 struct yenta_socket *socket = (struct yenta_socket *) data;
480 480
481 yenta_interrupt(0, (void *)socket, NULL); 481 yenta_interrupt(0, (void *)socket);
482 socket->poll_timer.expires = jiffies + HZ; 482 socket->poll_timer.expires = jiffies + HZ;
483 add_timer(&socket->poll_timer); 483 add_timer(&socket->poll_timer);
484} 484}
@@ -896,7 +896,7 @@ static unsigned int yenta_probe_irq(struct yenta_socket *socket, u32 isa_irq_mas
896#ifdef CONFIG_YENTA_TI 896#ifdef CONFIG_YENTA_TI
897 897
898/* interrupt handler, only used during probing */ 898/* interrupt handler, only used during probing */
899static irqreturn_t yenta_probe_handler(int irq, void *dev_id, struct pt_regs *regs) 899static irqreturn_t yenta_probe_handler(int irq, void *dev_id)
900{ 900{
901 struct yenta_socket *socket = (struct yenta_socket *) dev_id; 901 struct yenta_socket *socket = (struct yenta_socket *) dev_id;
902 u8 csc; 902 u8 csc;